Ultraviolet light filter



y 1941- B. H. CARROLL ETAL 2,241,239

ULTRAVIOLET LIGHT FILTER Filed Jan. 19, 1940 FILTER LAYER CONTAINING AN UNSATUMTED ARYL ACETOPHENONE.

SILVER HAL/DE EMULSION. SUPPORT.

v I E7861! ITIVE EMU s10. 7 I L 'ER MK /ER CONTAILHING AN 5 sxx i a mag UNSATURATEDARYLACETOPHENONE mmk3 snssn-ssusmvs EMULSION.

FILTER LAYER CONTAINING AN UNSATURATED ARYL ACETDPHENOHE RED-SENSITIVE EMULSION.

SUPPORT.

wmm

C YR/L J 6' 7741/0 [NVENTORS ATTORNEYS Patented ay 6, B41

2,241,239 UILVIOLE'JL LIGHT FILTER Application January 19, 1940, Serial No. 314,66

in Great Britain January 23, 1939 Claims.

This invention relates to filters for ultraviolet light and particularly to such filters as used with photographic sensitive material.

It is known that certain materials such as cellulosic films and photographic layers are afiected by ultraviolet light rays, these rays in the case of sensitive photographic layers sometimes caus ing an undesired exposure of the layer. Photographic silver halide emulsions are sensitive to blue, violet and ultraviolet regions of the spectrum in addition to any other sensitivity which may be given them and in the exposure of such material it is frequently desirable to prevent the action of ultraviolet light on the sensitive emulsion. This is especially true in the case of photographic material designed ior use in color photography where the film has been sensitized to the longerwave length regions and where it is desirable to record only the rays of the visible spectrum.

Ultraviolet absorbing materials have previously been used in filter layers for cellulosic film and photographic layers but many of these filter materials have been objectionable because they are decomposed by light and hence lose their light absorbing properties. It is, therefore, an object of the present invention to provide a novel ultraviolet filtering material for cellulosic film and photographic layers. It is a further object of the present invention to provide an ultraviolet filtering material which is not readily decomposed by visible or ultraviolet light rays. Other objects will appear from the following description of our invention.

These objects are accomplished by incorporating in gelatin or other colloidal material an unsaturated aryl acetophenone, and applying this material as a layer to the sheet or film desired tobeprotected. v

In the accompanying drawing. 1 is a sectional view of a single layer photographic film having an overcoated filtering layer made according to our invention and" Fig. 2' is a sectional view of a multi-layer photographic film having intermediate filter layers made according to our invention.

The compounds which we propose to use as ultraviolet absorbing materials are unsaturated aryl acetophenones of which the following ma be cited as specific examples:

Bonzal acctophenone Oarboxybenial eoetoplienone (Sodium salt) Anisal acetophenone SOaNfi I cmo-Ocn=on- H 3-Sulfoanisal acctophenonc (Sodium salt) Cinnamal ecetophcnonc millimicrons and absorb very little visible light.

In making a light filter according to our invention, a suitable amount of one or more of the unsaturated aryl acetophenones listed above is incorporated in a suitable colloidal material such as gelatin, agar, cellulose esters or ethers or synthetic resins. These resins include the polyvinyl esters, such as polymerized vinyl acetate which is known, for example, under the trade name Gelva, the preparation of which is described in the U. S. Patents Nos. 1,241,738, 1,586,803 and 1,710,825. A further type of resin which may be used is the polyvinyl acetal type. These resins are condensation products of partially or completely hydrolyzed polyvinyl acetate and an aldehyde, such as formaldehyde, acetaldehyde, or butyraldehyde, and are known as polyvinyl acetals. They are sold under various trade names, such as- Formvar and Alvar." A still further type of resin which I may use is the alkyd type, which is a condensation product of a polybasic acid and a polyhydroxy alcohol. An example of this type of resin is glypta which is a condensation product of glycerine and phthalic acid or phthalic anhydr-ide.

These ultraviolet filtering layers may be applied to photographic film wherever it is desirable to absorb ultraviolet light rays. They may be applied over a sensitive layer or between sensitive layers of a multi-layer photographic film or they may be applied to a finished photographic picture to preventdeterioration of the finished picture. They may also be applied to materials such as cellulose acetate sheeting or to other sheet material to prevent action of ultraviolet light on the material.

The following examples which are illustrative only indicate methods of coating an ultraviolet filter layer according to our invention:

Example 1 A solution of the sodium salt-of 3-sulioanisal acetophenone is prepared by dissolving 3.19

grams in 100 cc. of water plus 0.40 gram sodium Example 2 A solution of benzalacetophenone is prepared by dissolving 2.1 grams in 100 cc. of a solvent such as methanol. This solution is mixed With 200 cc. of a solution of a colloidal material such as cellulose acetate phthalate or polyvinyl phthalate, 10 grams per 100 cc., in a suitable solvent mixture such as 50 cc. methanol, 25 cc. acetone and 75 cc. of the methyl ether of ethylene glycol (methyl Cellosolve). This is then spread over a film at the rate of approximately- 10 cc. per 1000 sq. cm. and forms a layer which can be removed by treatment with an alkaline solution such as a photographic developer, with agitation.

Our invention will now be described with particular reference to the accompanying drawing. As shown in Fig. 1, a support it of any suitable material such as cellulose acetate, cellulose nitrate, synthetic resin or paper iscoated with a silver halide emulsion layer it and a filter layer B2 of gelatin or other colloidal material containing an unsaturated aryl acetophenone.

Fig. 2 shows another modification of our invention in which a transparent support it of any suitable transparent material such as cellulose nitrate or cellulose acetate carries silver halide emulsion layers i4, i5 and to sensitive respectively to the red, green and blue regions of the visible spectrum. Between emulsion layers M and lb and between emulsion layers l5 and it,

there are ultraviolet filter layers i'l containing an unsaturated aryl acetophenone. An element of this type is useful in a photographic process such .as that described in Schinzel U. S. application 223,948, filed August 9, 1938 in which the several sensitive layers are processed separately and it is desirable to prevent the action of ultraviolet light on the middle layer H5 at some stage in the processing. It is to be understood that this graphic element. Other uses will suggest themselves to those sln'lled in the art. It is to be un- 4 derstood that our invention may be used in other ways not herein specifically mentioned and that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. A film afiected by ultraviolet lig t having thereon a layer of a'colloidal material containing an unsaturated aryl acetophenone containing a chain having a conjugated system of double bonds, one of the terminal atoms of the chain being the oxygen atom of the acetophenone, uniformly dispersed therein.

2. A photographic element having thereon a. layer afiected by ultraviolet light and over said layer a layer of a colloidal material containing an unsaturated aryl acetophenone containing a methine chain which forms a conjugated system of double bonds with the carbonyl group of the acetophenone, uniformly dispersed therein.

3. A photographic element having thereon a layer sensitive to ultraviolet and visible light rays and over said sensitive layer a layer of a colloidal material containing an unsaturated aryl acetophenone containing a methine chain which forms a conjugated system of double bonds with the carbonyl group of the acetophenone, uniformly dispersed therein.

4. A photographic element having thereon a. gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing an unsaturated aryl acetophenone containing a methine chain which forms a conjugated system of double bonds with the carbonyl group of the acetophenone, uniformly dispersed therein.

5. A photographic element having thereon a. gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing a benzal acetophenone.

6. A photographic element having thereon a. gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing a carboxy benzal acetophenone.

7. A photographic element having thereon a gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing an anisal acetophenone.

8. A photographic element having thereon a. gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing a sulfoanisal acetophenone.

9. A photographic element having thereon a gelatin silver halide emulsion layer sensitive to ultraviolet and visible light rays and over said emulsion layer a layer of gelatin containing a cinnamal acetophenone.

10. A multi-layer photographic film comprising a transparent support having a. plurality of emulsion layers thereon and over at least one of said layers a layer of gelatin containing an unsaturated aryl acetophenone containing a methine chain which forms a conjugated system of double bonds with the carbonyl group of th acetophenone, uniformly dispersed therein.

BURT H. CARROLL. CYRIL J. STA'UD. 

